Medical ablation device and method of use

ABSTRACT

A tissue resection device includes an elongate shaft having a ceramic working end with a window and a wire-like electrode. A motor oscillates the electrode back and forth in an arc between opposing sides of the window. The working end is engaged against a tissue surface while radiofrequency current is delivered to the wire-like electrode to cut tissue received within the window. A negative pressure source may be connected to the window through an interior passageway in the elongate shaft to extract cut tissue from the working end.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/US16/25509 (Attorney Docket No. 48428-704.601), filed Apr. 1,2016, which claims priority from provisional application No. 62/154,595(Attorney Docket No. 48428-704.101), filed on Apr. 29, 2015, the fulldisclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

1. Field of the Invention

This invention relates to medical instruments and systems for applyingenergy to tissue, and more particularly relates to an electrosurgicaldevice adapted for cutting and extracting tissue in an endoscopicprocedure.

Various types of medical instruments utilizing radiofrequency (RF)energy, laser energy and the like have been developed for deliveringthermal energy to tissue, for example to ablate tissue and to cuttissue. Arthroscopic and other endoscopic electrosurgical tools oftencomprise treatment electrodes of different configurations where thetools may optionally be combined with irrigation and/or aspiration toolsfor performing particular minimally invasive procedures. Often thenature of the electrode limits use of a particular tool, and tools mustbe exchanged during a procedure to perform different tasks.

For these reasons, it would be desirable to provide new and differentdesigns for electrosurgical tools that allow the tools to bere-configured during a procedure to perform different tasks. At leastsome of these objectives will be met by the inventions described below.

2. Background Art

The disclosure of this application is similar to that of applicationSer. No. 13/857,068. Relevant patents and publications include U.S. Pat.No. 5,622,647; U.S. Pat. No. 5,672,174; and U.S. Pat. No. 7,824,398.

SUMMARY OF THE INVENTION

In a first aspect of the present invention, an electrosurgical devicecomprises an elongate shaft, typically a tubular shaft, having an axiswith an interior channel extending along the axis to an opening in adistal end of the shaft. The channel is configured to be coupled to anegative pressure source, and an electrode with a hook-shaped distalportion is coupled to the shaft and moveable between a first position inwhich a distal tip of the electrode is disposed at a periphery of theopening and a second position in which the distal tip extends distallybeyond the opening. With the distal portion of the electrode in thefirst position, the tool is particularly useful for surface ablation oftissue such as cartilage. With the distal portion of the electrode inthe second position, the tool is particularly useful for cutting tissuestructures. In one application, the hook-shaped electrode can be used ina lateral release, which is an arthroscopic procedure for releasingtight capsular structures, e.g., the lateral retinaculum, on the outeror lateral aspect of the kneecap. Such a procedure is performed due topain related to the kneecap being pulled over to the outer (lateral)side and not being able to move properly in a groove of the femur boneas the knee bends and straightens.

In a second aspect of the present invention, an electrosurgical devicecomprises an elongate shaft, typically tubular, that extends along anaxis with an interior channel extending to an opening with a peripheryin a working end. The channel is adapted to be coupled to a negativepressure source. A moveable electrode having a conductive portion with aproximal end and a distal end is coupled to the shaft so that the distalend of the conductive portion is located proximate the periphery of theopening when the electrode is in a proximally retracted position and thedistal end of the electrode extends distally beyond the periphery whenthe electrode is in a distally extended position. With the conductiveportion of the electrode in the first position, the tool is particularlyuseful for surface ablation of tissue and cautery. With the conductiveportion of the electrode in the second position, the tool isparticularly useful for capturing and cutting tissue structures.

Usually, in both aspects, the electrode of the electrosurgical device ismounted to axially translate between the first and second positions. Inanother variation, the electrode is mounted to rotate about the axisbetween the first and second positions. In another variation, theelectrode of the electrosurgical device of is mounted to axiallytranslate and/or rotate about the axis between the first and secondpositions.

In specific embodiments, the electrosurgical device may further comprisea valve in the interior channel for controlling fluid flow therethrough.An exterior of the electrosurgical shaft may comprise a secondelectrode. The electrosurgical device may further comprise a rotatorcoupled to the electrode, where the rotator causes the electrode torotate as it is being axially translated. The opening of theelectrosurgical device may define a plane which is angled relative tothe axis of the shaft, and the hook-shaped portion of the electrode maybe turned so that a back of the hook portion extends outwardly above theplane when the electrode is in the first position. The electrosurgicaldevice may still further comprise a temperature sensor and/or impedancesensing electrodes near a distal end of the shaft. Alternatively, or inaddition to the sensors, the electrosurgical device may further comprisea temperature-responsive current limiting element in series with theelectrode in order to inhibit or prevent overheating of distention fluidin a treatment site.

In a first specific embodiment, the elongate shaft of theelectrosurgical device comprises a ceramic or other tubular bodyextending along an axis and having a window in a distal portion thereof.The electrode comprises a wire-like electrode configured to rotate in anarc back and forth between opposing sides of the window, i.e. torotationally oscillate about an axis of the shaft. A motor isoperatively connected to the wire-like electrode to rotate orrotationally oscillate the wire-like electrode to cut tissue received inthe window. The arc of oscillation will typically be in the range from10° to 210°, often in the range from 20° to 180°. The oscillation cyclemay be in the range from 1 to 100 CPS (Hz), typically being from 5 to 50CPS. The oscillation rate will typically be adjustable, and theapparatus of the present invention may include a mechanism for effectingsuch adjustment and/or the motor speed may be controllable. Inparticular embodiments, the device includes a mechanism that provides afirst rate of rotating the electrode in a first rotational direction anda second rate of rotating the electrode in a second opposing rotationaldirection.

In additional embodiments, the electrosurgical device will be configuredto be connected to radiofrequency (RF) source to couple the wire-likeelectrode to the RF source. Additionally, an interior passageway of theshaft may be connected to communicate with a negative pressure source tohelp remove excised tissue from the passageway.

In certain embodiments, the wire-electrode of the electrosurgical devicemay be configured to abut opposing sides of the window at the end ofeach arc of oscillation. Alternatively, the electrode may be configuredto move past the opposing sides of the window in a shearing motion atthe end of each cycle of oscillation. The electrosurgical device mayfurther comprise a rotatable drive shaft operatively coupling thewire-like electrode to the motor, said shaft including a shock absorbermechanism to absorb a rotational resistance.

In other specific embodiments, the elongate shaft may comprise anarticulating shaft configured to be actuated by a one pull-wire topermit steering of the cutting end during use. Optionally, thewire-electrode may be configured to be moved axially (in addition to theoscillatory motion) relative to the window. Additionally, the wire-likeelectrode will typically have a hook shape and the elongate shaft willusually have a channel configured to be removably connected to a fluidto deliver a fluid to a distal portion of the shaft.

In a second specific embodiment, the electrosurgical device comprises anelongate shaft with a longitudinal axis end and a distal working endcomprising a ceramic body with a window therein. A wire-like electrodeis mounted proximate the window and is configured to rotationallyoscillate in an arc back and forth between opposing sides of the windowto cut tissue received by the window. A motor oscillates the wire-likeelectrode, and a negative pressure source is coupled to a passageway inthe shaft communicating with the window. In particular embodiments, thewindow will be faced or oriented perpendicularly or at an acute angle(greater than 45°, optionally greater than 60°) relative to thelongitudinal axis of the elongate shaft. Optionally, the distal workingend of the elongate shaft may be configured to provide an articulating(steerable) working end

In specific aspects of the second embodiment, the articulating workingend of the shaft may comprise a slotted tube actuated by at least onepull-wire. A radiofrequency (RF) current source may be operativelycoupled to the electrode, and the elongate shaft will typically have achannel configured to be connected to a fluid source to deliver a fluidthrough an open port in the working end.

Systems according to the present invention may include a controlleradapted to control at least one of the motor operating parameters, theRF source, the negative pressure source, and the fluid source based on afeedback signal. The feedback signal may be provided by the controllerin response sensing an operating parameter from at least one of themotor, the RF source, the negative pressure source and the fluid source.In many embodiments, the controller will be configured to adjust atleast one of (1) the motor operating parameters in response to feedbacksignals from at least one of the RF source and the negative pressuresource, (2) the RF parameters in response to feedback signals from atleast one of the motor operating parameters and the negative pressuresource., and (3) the negative pressure parameters in response tofeedback signals from at least one of the motor operating parameters andthe RF source. The electrode may be configured to axially translatebetween the first and second positions, and the electrode usually has ahook shape.

In a third specific embodiment, a method for resecting tissue comprisesproviding an elongate shaft with a working end which typically comprisesa tubular or other ceramic body having a window and a motor drivenelectrode. The electrode is oscillated back and forth in an arc betweenopposing sides of the window. The working end is engaged against thetissue to cause a volume of tissue to pass through the window, and an RFsource delivers RF current to the electrode to cut tissue receivedthrough the window. The resected tissue passes into a passageway in theelongate shaft.

In particular aspects of the methods of the present invention, anegative pressure source in communication with the interior passagewayin the elongate shaft may be actuated to extract cut tissue from theworking end through the interior passageway in the elongate shaft. Thetissue may be immersed in a liquid which may optionally be delivered tothe tissue from a fluid source to the working end through a flow channelin the elongate shaft. Alternatively, the tissue may be maintainedpresent in a gas environment while resecting the tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is side view of an electrosurgical probe corresponding to theinvention that includes an elongate shaft extending along an axis to aworking end with a re-configurable electrode.

FIGS. 1B and 1C illustrate various embodiments of the re-configurableelectrode of FIG. 1.

FIG. 2A is a perspective view of the working end of FIG. 1 with themoveable electrode in a first position.

FIG. 2B is a perspective view of the working end of FIG. 1 with themoveable electrode in a second position.

FIG. 2C is a perspective view of the working end of FIG. 1 with themoveable electrode in a third position.

FIG. 3 is an exploded view of the components of the working end of FIG.1.

FIG. 4 is a perspective view of a working end of an electrosurgicaldevice similar to that of FIG. 1 with temperature sensor for measuringthe temperature of distention fluid in a joint and a controller that cansignal an LED to illuminate as a high temperature alert to thephysician.

FIG. 5 is a perspective view of the working end of an electrosurgicaldevice similar to that of FIG. 1 with a second electrode arrangementconfigured to measure impedance in distention fluid in a joint in orderto determine the temperature of the fluid.

FIG. 6A is a cut-away perspective view of the working end of an ablationdevice similar to that of FIG. 1 with a PTCR (positive temperaturecoefficient of resistance) material in the return electrode assemblywhich can sense distention fluid temperature to de-activate theelectrical path from the return electrode to the RF source.

FIG. 6B is another cut-away view of the working end of FIG. 6A showingan inner sleeve that carries the working end assembly.

FIG. 7 is a perspective view of another variation of an electrosurgicaldevice similar to that of FIG. 1 with a rotatable electrode that isdriven by a motor to rotate back and forth in an arc.

FIG. 8 is a cut-away view of the device of FIG. 7 showing a motor anddrive mechanism.

FIG. 9 is a perspective view of the working end of the device of FIG. 7.

FIG. 10 is a perspective view of the electrode of the device of FIG. 7de-mated from the shaft assembly.

FIG. 11 is a perspective view of the electrode and distal ceramic bodyof the device of FIG. 7.

FIG. 12A is a cross-sectional view of the working end the device of FIG.9 taken along line 12-12 of FIG. 9, wherein the electrode abuts edges ofa ceramic body at the ends of its movement in an arc.

FIG. 12B is a cross-sectional view of a working end similar to that ofFIG. 12A wherein the electrode moves past edges of a ceramic body in ashearing motion at the ends of it movement in an arc.

FIG. 13 is a perspective view of a working end of an electrosurgicaldevice similar to that of FIGS. 1 and 7 with an articulating shaftportion.

FIG. 14 is a perspective view of another variation of working endsimilar to that of FIG. 9 with a fluid source for delivering fluid tothe electrode and the working end.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings and the reference numbers marked thereon,FIGS. 1A and 2A-2C illustrate one embodiment of electrosurgical probe100 that includes a handle portion 104 and an elongate shaft 105 thatextends about longitudinal axis 108. FIG. 1 is a schematic view of theprobe in which the shaft 105 consists of an assembly further describedbelow having a diameter ranging from about 3.0 mm to 6.0 mm and anysuitable length for arthroscopy or another endoscopic procedure. Theworking end 110 carries an electrode arrangement including a moveablefirst polarity or active electrode 120 and a second polarity or returnelectrode 122 operatively coupled to an RF source 125 and controller130. As can be seen in FIG. 1A, the shaft 105 has a fluid extractionchannel 132 in communication with a negative pressure source 135 thatcan be a wall suction source in an operating room or a pump system incontroller 130. In FIG. 2A, it can be seen that fluid channel 132extends distally to an opening 140 in the working end 110 which isproximate the electrode 120.

In one embodiment in FIGS. 1A and 2A-2C, the first polarity electrode120 has an elongated medial portion 142 that extends through apassageway 144 (or channel 132) in shaft 105 to an actuator mechanism146 in the handle 104. The electrode 120 terminates in an electricallyconductive portion free from insulation, with the conductive portiontypically being hook-shaped as described in more detail below. In FIG.1A, it can be seen that actuator 146 is adapted to slide from position Ato position B to position C to thereby move the electrode 120 from thenon-extended position of FIG. 2A to the extended position of FIG. 2B andthen to the extended and rotated position of FIG. 2C. Any suitableactuator mechanism known in the art can be used to move the electrode120 axially and rotationally, and in one variation shown in FIG. 1, abarrel 148 with a spiral groove 152 therein can translate linear motionof the actuator mechanism 146 to rotational motion. In anotherembodiment, the actuator 146 can be fixed to the proximal end 149 ofelectrode 120 and adapted to move both axially and rotationally to movethe electrode 120 between the various positions shown in FIGS. 2A-2C.The moveable actuator 146 can be configured with detents that engages aportion of handle 104 to releaseably maintain the electrode 120 in oneof the selected positions of FIGS. 2A-2C.

Referring again to FIG. 1A, a second actuator 160 in handle 104 isadapted to modulate outflows in fluid extraction channel 132. FIG. 1Ashows the extraction channel portion 132′ in handle 104 extends to aquick-connect 162 on handle 104 to which an outflow tubing 164 iscoupled that extends to the negative pressure source 135. The actuator160 can operate any type of suitable valve 165 to control the amount ofoutflow from a treatment site, such as a knee or shoulder. In such anarthroscopic procedure, the fluid inflows are provided through anindependent inflow path which can be through a fluid channel in anendoscope or through another independent cannula accessing the treatmentsite.

Still referring to FIG. 1A, an electrical cable 166 extends from RFsource 125 and controller 130 to the handle 104 with leads in the handlecoupled to the first and second electrodes. The system can include afootswitch 168 operatively connected to controller 130 for ON-OFFactuation of RF energy to the electrode arrangement. In anothervariation, the switch for actuation of RF energy can be positioned inthe probe handle 104. The RF source and controller can provide forvarious power setting as is known in the art, and can use anyradiofrequency known in the art for creating a plasma about theelectrode 120 for cutting tissue.

Referring to FIGS. 1B and 1C, the active electrode 120 which includesthe conductive portion of the electrode extending distally from themedial portion 142 is typically hook-shaped and may have an a square ortrapezoidal profile, as shown in FIG. 1B, or may have a curved orarcuate profile, as shown in FIG. 1C. The hook portion will typicallyhave a length L in the range from 3 mm to 10 mm and a depth X in therange from 2 mm to 6 mm. The hook-shaped active electrode will alsoinclude a back or a spine region 121 that remains exposed over a planedefined by the opening 140 when the electrode is proximally retractedand a distal tip 190 of the electrode engages or lies proximate to theperiphery or perimeter 192 surrounding the opening 140. The distal tip190 may terminate at, above, or below a centerline 123 of the electrode,as shown in full line and broken lines in FIGS. 1B and 1C.

The exploded view of a portion of the probe of FIG. 3 illustrates thecomponents and assembly of the working end 110. In one variation shownin FIG. 3, the shaft 105 includes an elongate metal sleeve 170 (e.g.,stainless steel) that is coupled to handle 104 which provides structuralstrength to the shaft 105 and further serves an electrical conductor tofunction as, or connect to, the return electrode 122. The proximal endof sleeve 170 is fixed to handle 104 with an electrical connector (notshown) within the handle coupling the sleeve 170 to cable 166 and a poleof the RF source 125 (see FIG. 1).

In FIG. 3, it can be seen that the distal end 174 of sleeve 170 coupleswith non-conductive ceramic body 175, which may be formed from amaterial selected from a group consisting of zirconia, alumina oranother similar ceramic, for example being yttria-stabilized zirconia,magnesia-stabilized zirconia, ceria-stabilized zirconia, zirconiatoughened alumina, or silicon nitride. In one variation, a reduceddiameter proximal end 177 of ceramic body 175 can mate with bore 180 insleeve 170. FIG. 3 further shows a metal distal body or housing 185 thatis configured to slide over ceramic body 175 as a support structure andthen is welded to the distal end 174 of sleeve 170 to thus provide theassembled working end of FIG. 2A-2C. The metal distal body or housing185 then functions as second polarity electrode 122 as can be understoodfrom FIG. 2A-2C. In one variation, a thin-wall dielectric material 186such a heat shrink material (PFA, FEP or the like) covers the sleeve 170proximally from the distal metal housing 185 to the handle 104.

In FIG. 3, it can be seen that first polarity electrode 120 and moreparticularly its medial portion 142 extends through a bore 189 inceramic body 175. The elongated portion of electrode 120 is covered by aheat-shrink insulator 187 of a material such as FEP or PFA. The distalportion of electrode 120 is configured with bends or curvature toprovide a hook-shaped electrode with an outermost electrode surface 188that is approximately within an envelope defined by the cylindricalperiphery of shaft 105 in the position of FIG. 2A. This configurationpermits the physician to move or “paint” the outermost surface 188 ofelectrode 120 across a tissue surface to perform an electrosurgicalsurface ablation of such tissue. Referring to FIGS. 2A and 3, the distaltip 190 of electrode 120 in the position shown in FIG. 2A is configuredto be disposed within or adjacent a periphery or perimeter 192 ofopening 140 in the working end. More particularly, distal tip 190 in theposition of FIG. 2A is configured to rest in a notch 194 in ceramic body175. When the distal tip 190 is in the position of FIG. 2A, the tip 190is distance D of at least 0.010″ (see FIG. 2A) from the closest edge ofwindow 195 of the metal body 185. As can be seen in FIGS. 2A-2C, thewindow edge 195 of metal body 185 is configured to have notch 200 thatis larger than the notch 194 in ceramic body 175 to insure that thefirst and second electrodes, 120 and 122, are not in close proximity inthe electrode position shown in FIG. 2A.

As can be seen in FIGS. 2B and 2C, the hook-shaped distal portion ofelectrode 120 can be extended axially and optionally rotationally toorient the distal tip 190 and terminal hook portion 196 forelectrosurgical cutting of tissue as is known in the art using hookelectrode tools. Thus, the electrode 120 is re-configurable to performelectrosurgical surface ablation treatments or electrosurgical cuttingtreatments. The electrode 120 can be a wire formed of tungsten,stainless steel or any other suitable material having a round, oval orpolygonal cross section.

Referring again to FIG. 3, in one variation, it can be seen that thebore 180 in sleeve 170 is lined with a thin-wall dielectric material 198such a Teflon® (PTFE), Nylon, PFA, FEP, polyethylene or the like whichprevents the inner wall of sleeve 170 from functioning as an electrode.In another aspect of the invention, FIG. 4 illustrates a temperaturesensing and signaling system that is carried within the working end 220of a probe similar to that of FIGS. 1-3. Temperature sensing ofdistention fluid in an arthroscopic procedure is important as the fluidcan be heated during any electrosurgical ablation procedure. If thedistention fluid is at an elevated temperature for an excessive timeperiod, tissue throughout the joint can be damaged. In FIG. 4, it can beseen a temperature sensor 225 is provided in a surface of the workingend which can comprise any form of thermocouple, thermistor or othertype of sensor. The sensor 225 is configured to send temperature signalsto the controller 130 which can signal the operator of elevatedtemperature and/or terminate energy delivery from the RF source to theworking end 220. In one variation shown in FIG. 5, the controller 130can signal the physician of a high temperature signal from sensor 225 byilluminating LED lights 240 a and 240 b coupled to electrical source 245on either side of the working end 220. In such an embodiment, thecontroller 130 may have algorithms for blinking the LEDs at increasingrates that increase with temperature of the distention fluid. Anycombination of visual, aural and tactile signals may be used to alertthe physician of elevated temperatures in the distention fluid. Inanother embodiment (not shown), the temperature sensor 225 can actuateat least one light source in the controller that is coupled to opticalfibers to carry light to light emitters in the working end. In anothervariation, a plurality of different wavelength light sources in thecontroller can send different wavelengths to the emitter(s) in theworking end to indicate different temperatures of the distention fluid.

FIG. 5 illustrates another temperature sensing system that can becarried by the working end 220 as in FIG. 5. In FIG. 5, spaced apartfirst and second electrodes, 252 a and 252 b are provided in insulatedsurface 254 of the probe shaft 255. The electrodes 252 a and 252 b arecoupled to an electrical source 255 and controller 130 which isconfigured to measure an electrical parameter of the distention fluid,for example impedance or capacitance of a saline distention fluid. Themeasured electrical parameter then can be compared to known values ofsaline at various temperatures in a look-up table to determine fluidtemperature. The calculated temperature then can actuate any visual,aural or tactile signal to alert the physician of elevated temperaturesin the saline.

FIGS. 6A-6B illustrate another system embodiment that integrates atemperature sensing mechanism with the return electrode to controlenergy delivery to tissue. As can be seen in FIG. 6A, the working 260 ofa probe is similar to that of FIGS. 1-3. However, the distal metalhousing 265 does not function as a return electrode. The metal housing265 is not welded to elongate sleeve 270 which is electrically coupledto RF source 125 and controller 130. Rather, an independent returnelectrode sleeve 275 with a short length is positioned proximally fromthe distal metal housing 265. In one variation, an insulative ceramiccollar 277 separates the distal metal housing 265 from the returnelectrode sleeve 275. The temperature-sensing component of the workingend 260 comprises a polymer PTCR (positive temperature coefficient ofresistance) sleeve 280 forms an intermediate electrical connectorbetween the return electrode sleeve 275 and sleeve 270 which iselectrically coupled to RF source 125 (see FIG. 1). The return electrodesleeve 275, the PTCR sleeve 280 and sleeve 270 can be mounted overinsulated support sleeve 285 shown in FIG. 6B. The PTCR material ofsleeve 280 allows conduction of RF current therethrough within aselected low temperature range, but can prevent current flow through thesleeve at a selected elevated temperature. As can be seen in FIGS.6A-6B, the proximal end 282 of the return electrode 275, the PTCR sleeve280 and the elongate sleeve 270 is covered with a thin-wall insulator288 to thus prevent conductive saline contact with this portion of theprobe. As can be understood in FIGS. 6A-6B, the thin-wall insulator 288allows heat transfer from the distention fluid through the insulator 288to the PTCR sleeve 280 which then can cause the PTCR sleeve to becomenon-conductive to terminate current flow from the return electrode 275to the RF source 125. By this means, the PTCR mechanism can terminate RFenergy delivery in response to elevated temperatures in the distentionfluid. The PTCR material can be selected to have a any suitableswitching temperature, for example any temperature between about 40° C.and 45° C. Suitable polymer PTCR materials can be fabricated by Bourns,Inc. 3910 Freedom Circle, Ste. 102, Santa Clara, Calif. 95954.

FIGS. 7-9 illustrate another variation of electrosurgical device 400that has a similar working end 410 with a hook-shaped electrode 415 butthis variation includes a motor 420 for driving the electroderotationally in an arc to cut tissue in the window 422 (FIG. 9) of theworking end. In this variation, a handle portion 424 is connected toelongate shaft 425 that extends about longitudinal axis 428. FIGS. 7-9are schematic views of the device wherein the shaft 425 consists againconsists of an assembly can have a diameter ranging from about 3.0 mm to6.0 mm for arthroscopic procedures and can range up to 10 mm or 15 mm indiameter for other endoscopic procedure. The working end 410 again has awire-like electrode 425 that can be extended to axially to use as a hookas described previously. The working end 410 comprises a ceramic body426 which can be a form of zirconia, alumina or another similar ceramicas described previously. The electrode 425 comprises a first polarity oractive electrode and the second polarity or return electrode 440 can bean outer surface of at least a portion shaft 425. The electrode 415 isoperatively coupled to an RF source 445 and controller 450. The shaft425 again has a fluid extraction channel or passageway 452 incommunication with a negative pressure source 455 that can be a wallsuction source in an operating room or a pump system in controller 450.As can be seen in FIG. 9, the fluid extraction channel 452 extendsdistally to the window 422 in the working end 410 which is below theelectrode 415.

In general, the electrosurgical device corresponding to the inventioncomprises a proximal handle 424 coupled to an elongate shaft 425extending along an axis 428 to a window 422 in a distal ceramic body 426forming a portion of the shaft and a wire-like electrode 415 driven by amotor 420 to rotate in an arc back and forth between opposing sides 460a and 460 b of window 422 to cut tissue received by the window. Thetissue can be suctioned into the window by the negative pressure source455. FIG. 8 shows a cut-away view of handle 424 with motor 420 therein.The motor is connected to a mechanism 464 that converts the motorsrotational motion to a back and forth movement of the electrode the arcshown in FIG. 12. In one variation, the electrode 415 can move in an arcthat ranges between 10° and 210° to cooperate with a window 422 that hasthe corresponding dimensional arc. In another variation, the electrodearc ranges between 20° and 180°.

The motor 420 can be electric and is geared to rotate or rotationallyoscillate the electrode 415 in a back and forth cycle at a rate between1 cycle per second (CPS or Hz) and 100 cycles per second. The system canbe actuated by an actuator or trigger 470 in handle 424. In onevariation, the actuator can include a variable speed mechanism foradjusting the rate of rotating or oscillating the electrode 415 back andforth. In another variation, the electrosurgical device 400 can includea mechanism for providing a first rate of rotating the electrode in afirst rotational direction and a second rate of rotating the electrodein a second opposing rotational direction. During operation, the RFsource and electrode can be activated in a first mode or cutting mode asis known in the art.

As can be understood from FIGS. 7-9, the controller 450 is adapted tocontrol the motor, the RF source and the negative pressure source, andin one variation the controller is configured to adjust RF parameters inresponse to feedback signals from at least one of the motor's operatingparameters and the negative pressure source. In another variation, thecontroller is configured to adjust motor operating parameters inresponse to feedback signals from at least one of the RF source and thenegative pressure source. In another variation, the controller isconfigured to adjust negative pressure parameters in response tofeedback signals from at least one of the motor operating parameters andthe RF source.

In another variation, the device 400 and controller upon de-activationof the actuator will stop rotation of the electrode in a selectedposition relative to the window, for example in the middle of the windowas shown in FIG. 9 or at an edge of the window. In either orientation,the electrode can be activated in a second or “coagulation” mode forcoagulating tissue as known in the art.

In a further variation as shown in FIG. 12A, the electrode 415 isadapted to rotationally oscillate within the window so that theelectrode abuts opposing sides 460 a and 460 b of window 422 at the endof each arc of rotation. In another variation as shown in FIG. 12B), theelectrode 415 can be configured to sweep past the opposing sides 460 aand 460 b of window 422 in a shearing motion at the end of each arc ofrotation.

FIGS. 8, 10 and 11 schematically show electrode 415 coupled to arotatable drive shaft 472 that is operatively coupled to motor 420,wherein the shaft 472 includes a shock absorber mechanism 474 to absorba rotational resistance such as when the electrode is rotated to abut aside of the window. The shock absorber mechanism 474 can be a spring orresilient drive shaft as is known in the art.

In general, a method of the present invention for resecting tissuecomprises providing an elongate member or shaft having a ceramic workingend with a laterally disposed window, e.g. an opening or cut-out in awall of the working end of the elongate member or an opening in a distalceramic body which faces perpendicularly or at an acute angle relativeto a longitudinal axis of the working end, and a motor driven electrodeadapted to rotate back and forth in an arc between opposing sides of thewindow, positioning the working end in an interface with tissue, andactuating the motor and an RF source to thereby cut tissue received bythe window with the moving electrode, resulting in pieces or “chips” ofcut tissue in an interior of the working end. The method may furthercomprise actuating a negative pressure source to extract the pieces or“chips” of tissue from the working end through the interior passagewayin the elongate shaft. In some embodiments, the method can be performedwith tissue interface submerged in saline or other electricallyconductive liquid. In other embodiments, the method can be performed ina gas environment, typically with saline or other electricallyconductive liquid being delivered from an external source to the workingend through a flow channel in the elongate shaft.

FIG. 13 shows another variation of the electrosurgical device with anarticulating shaft portion 478 proximate to the working end 410. Thearticulating shaft can be actuated by a pull-wire 479 in a slotted tubeas is known in the art.

FIG. 14 shows another variation of the electrosurgical device wherein afluid source 480, such as saline, is provided in fluid communicationwith a flow channel 482 in the shaft 425 to deliver fluid to the workingend and electrode 415. The inflow of fluid can provide fluid to flowthrough the device to assist in extracting cut tissue, or can be use toflood the electrode if operating in a gas environment. In anothervariation, the electrode (not shown) can be a hollow tube coupled to thefluid source 480 with the electrode 415 having one or more ports forfluid flow therethrough in the exposed electrode portion that cutstissue in the window.

Although particular embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration and the above description of theinvention is not exhaustive. Specific features of the invention areshown in some drawings and not in others, and this is for convenienceonly and any feature may be combined with another in accordance with theinvention. A number of variations and alternatives will be apparent toone having ordinary skills in the art. Such alternatives and variationsare intended to be included within the scope of the claims. Particularfeatures that are presented in dependent claims can be combined and fallwithin the scope of the invention. The invention also encompassesembodiments as if dependent claims were alternatively written in amultiple dependent claim format with reference to other independentclaims.

What is claimed is:
 1. An electrosurgical device comprising: an elongate shaft having an axis and a window in a distal portion thereof; a wire-like electrode configured to rotationally oscillate in an arc back and forth between opposing sides of the window; and a motor operatively connected to the wire-like electrode to rotationally oscillate the wire-like electrode to cut tissue received in the window.
 2. The electrosurgical device of claim 1 wherein the distal portion comprises a ceramic material.
 3. The electrosurgical device of claim 1 wherein the arc ranges between 60° and 210°.
 4. The electrosurgical device of claim 1 wherein the arc ranges between 90° and 180°.
 5. The electrosurgical device of claim 1 wherein the electrode is rotationally oscillated in a back and forth cycle at a rate between 1 cycle per second and 50 cycles per second.
 6. The electrosurgical device of claim 1 wherein the device is configured to allow adjustment of the electrode oscillation rate.
 7. The electrosurgical device of claim 1 wherein the device is configured to rotationally oscillate at a first rate in one direction and at a second rate in another direction.
 8. The electrosurgical device of claim 1 further comprising an RF source operatively coupled to the electrode.
 9. The electrosurgical device of claim 8 further comprising a negative pressure source communicating with an interior passageway in the elongate shaft.
 10. The electrosurgical device of claim 9 further comprising a controller adapted to control the motor operating parameters, the RF source, and the negative pressure source.
 11. The electrosurgical device of claim 10 wherein the controller is configured to adjust at least one of (1) the motor operating parameters in response to feedback signals from at least one of the RF source and the negative pressure source, (2) the RF parameters in response to feedback signals from at least one of the motor operating parameters and the negative pressure source, and (3) the negative pressure parameters in response to feedback signals from at least one of the motor operating parameters and the RF source.
 12. The electrosurgical device of claim 10 wherein the controller is configured to stop rotation in a selected position relative to the window.
 13. The electrosurgical device of claim 12, wherein the controller is configured to deliver coagulation RF energy to tissue when the electrode is in the stopped position.
 14. The electrosurgical device of claim 1 wherein the electrode abuts opposing sides of the window at the end of each arc of rotation.
 15. The electrosurgical device of claim 1 wherein the electrode is configured to move past the opposing sides of the window in a shearing motion at the end of each oscillation.
 16. The electrosurgical device of claim 1 further comprising a rotatable drive shaft operatively coupling the wire-like electrode to the motor, said shaft including a shock absorber mechanism to absorb a rotational resistance.
 17. The electrosurgical device of claim 1 wherein the elongate shaft is configured to be articulated by a pull-wire.
 18. The electrosurgical device of claim 1 wherein the wire-electrode is configured to be moved axially relative to the window.
 19. The electrosurgical device of claim 1 wherein the wire-like electrode has a hook shape.
 20. The electrosurgical device of claim 1 wherein the elongate shaft has a channel configured to be removably connected to a fluid to deliver a fluid to a distal portion of the shaft.
 21. An electrosurgical device comprising: an elongate shaft having a longitudinal axis and a distal working end comprising a ceramic body with a window therein; a wire-like electrode configured to be driven by a motor to rotationally oscillate in an arc back and forth between opposing sides of the window to cut tissue received by the window; and a negative pressure source coupled to a passageway in the shaft communicating with the window.
 22. The electrosurgical device of claim 21 wherein widow faces perpendicularly or at an acute angle relative to the longitudinal axis.
 23. The electrosurgical device of claim 21 further comprising a radiofrequency (RF) current source RF source operatively coupled to the electrode.
 24. The electrosurgical device of claim 21 wherein the elongate shaft has a channel configured to be connected to a fluid source to deliver a fluid through an open port in the working end.
 25. The electrosurgical device of claim 24 further comprising a controller adapted to control at least one of the motor operating parameters, the RF source, the negative pressure source, and the fluid source based on a feedback signal.
 26. The electrosurgical device of claim 24 wherein the feedback signal is provided by the controller sensing an operating parameter from at least one of the motor, the RF source, the negative pressure source and the fluid source.
 27. The electrosurgical device of claim 24 wherein the controller is configured to adjust at least one of (1) the motor operating parameters in response to feedback signals from at least one of the RF source and the negative pressure source, (2) the RF parameters in response to feedback signals from at least one of the motor operating parameters and the negative pressure source, and (3) the negative pressure parameters in response to feedback signals from at least one of the motor operating parameters and the RF source.
 28. The electrosurgical device of claim 20 wherein the electrode is configured to axially translate between the first and second positions.
 29. A method of resecting tissue, comprising: providing an elongate shaft with a working end having a window and a motor driven electrode adapted to oscillate back and forth in an arc between opposing sides of the window; positioning the working end against the tissue to cause tissue to interface with the window; and actuating the motor and an RF source to cut tissue interfacing with the window with the oscillating electrode, wherein the cut tissue enters an interior in the elongate shaft.
 30. The method of claim 29 further comprising actuating a negative pressure source in communication with the interior passageway in the elongate shaft to extract cut tissue from the working end through the interior passageway in the elongate shaft. 